I've played both melee DPS cleric and melee DPS paladin a ton, so here's my thoughts -
Paladin is much better for solo'ing. It has better melee DPS than cleric, solid self heals and amazing self only buffs. KotC is a way better DPS tree than Warpriest. It you are solo'ing absolutely go Pally. Pally is just better in most situations because it brings better DPS and has plenty of self heals and way better survivability since it has sacred defender access and divine grace. Most people will be much better off going Pally.
Melee cleric really needs to be played in groups to make it worth using instead of pally. You won't have as much DPS or survivability but it does have a lot more versatility and brings helpful things to a group. It has a wide array of helpful party buffs pally doesn't get like TS, FoM, Holy Aura. Multiple quicken-able Res spells to get the party up fast in hairy situations. Radiance in tier 5 RS is super helpful to parties. In most situations Paladin is better but Melee Cleric can have RS aura going at all times for passive heals and multiple spammable mass cures with no max caster levels through tier 5 RS. War domain gives them Holy Sword to make up a lot of DPS. Main advantage melee cleric has over pally is ability to function as a party healer in addition to doing solid DPS, and bring essential party buffs. Now that said I think if you don't go tier 5 radiant servant you may as well just play pally instead, despite tier 5 RS just being OK. On melee cleric I typically don't use Warpriest much at all and instead go WIS based, tier 4 Falconry.
In either case don't plan on doing any offensive spellcasting. If you're going to play a melee cleric you need to go all in on melee DPS. Or if an offensive caster, go all in on that. There aren't enough feat and gear slots to go around to be good at both offensive casting and melee - trying to do both ends with you being mediocre at both IMO. And Cleric doesn't have any good passive DPS so you can't justify the opportunity cost of time spent casting spells when your melee DPS is way better, or vice versa, if building an offensive caster. If you want to be a hybrid caster/melee, arcanes do that better.